Carbohydrate deficient transferrin in the assessment of alcohol misuse: absolute or relative measurements? A comparison of two methods with regard to total transferrin concentration

The association between an energy-adjusted dietary inflammatory index and inflammation in rural and urban Black South Africans

OBJECTIVE

To quantify the inflammatory potential of the diet of rural and urban Black South Africans using an adapted energy-adjusted dietary inflammatory index (AE-DII) and to investigate its relationship with inflammatory and cardio-metabolic disease risk markers. Dietary inflammatory potential has not been investigated in African populations.

DESIGN

Cross-sectional investigation.

SETTING

Rural and urban sites in the North West province of South Africa.

PARTICIPANTS

1885 randomly selected, apparently healthy Black South Africans older than 30 years.

RESULTS

AE-DII scores ranged from -3·71 to +5·08 with a mean of +0·37. AE-DII scores were significantly higher in men (0·47 ± 1·19) than in women (0·32 ± 1·29), and in rural (0·55 ± 1·29) than urban participants (0·21 ± 1·19). Apart from its dietary constituents, AE-DII scores are primarily associated with age, rural-urban status and education. Contrary to the literature, alcohol consumption was positively associated with AE-DII scores. Of the four tested inflammatory and thirteen cardio-metabolic biomarkers, the AE-DII was only significantly negatively associated with albumin and HDL cholesterol, and positively with waist circumference and fasting glucose, upon full adjustment.

CONCLUSION

Rural men consumed the most pro-inflammatory diet, and urban women the least pro-inflammatory diet. The diet of the participants was not overtly pro- or anti-inflammatory and was not associated with measured inflammatory markers. The inflammatory potential of alcohol at different levels of intake requires further research. Understanding dietary inflammatory potential in the context of food insecurity, unhealthy lifestyle practices and lack of dietary variety remains limited.

The diagnostic power of direct carbohydrate-deficient transferrin immunoassay in alcoholics. Absolute or relative values?

The objective of this study was to compare the diagnostic power of direct carbohydrate-deficient transferrin (CDT) immunoassay in alcohol abuse expressed in relative units with the diagnostic power of the results expressed in absolute units. Serum CDT was determined in 127 alcoholics using N Latex CDT direct immunonephelometric assay (Siemens Healthcare Diagnostics, Marburg, Germany). The diagnostic sensitivity, specificity, negative and positive predictive value, and also the positive and negative likelihood ratios do not differ between results expressed in relative or absolute units independently of cutoff chosen. Finally, the area under the receiver operating characteristic (ROC) curves for N Latex CDT test expressed in absolute units does not differ from the area for results expressed in relative units. We conclude that the diagnostic usefulness of N Latex immunonephelometric assay using the relative or absolute values is the same.

Biomarkers in alcoholism

Alcoholism ranks as one of the main current threats to the health and safety of people in most Western countries. Therefore, a high priority should be given to aims at reducing its prevalence through more effective diagnosis and early intervention. The need for objective methods for revealing alcohol abuse in its early phase has also been widely acknowledged. It is postulated here that the diagnosis of alcohol use disorders could be markedly improved by a more systematic use of specific questionnaires and laboratory tests, including blood ethanol, serum gamma-glutamyltransferase (GGT), carbohydrate-deficient transferrin (CDT), and mean corpuscular volume of erythrocytes (MCV). Recent research has provided new insights into the relationships between ethanol intake, biomarkers, and factors affecting their diagnostic validation, including gender, age, and the effects of moderate drinking and obesity. It appears that the concept of reference intervals for several ethanol-sensitive parameters in laboratory medicine needs to be revisited. CDT is currently the most specific marker of alcohol abuse, and when combined with GGT using a mathematically formulated equation a high sensitivity is reached without loss of assay specificity. Possible new biomarkers include minor ethanol metabolites (protein-acetaldehyde condensates and associated autoimmune responses, ethylglucuronide, and phosphatidylethanolamine), 5-hydroxytryptophol, and genetic markers although so far their routine applications have been limited.

Biomarkers of alcohol consumption in patients classified according to the degree of liver disease severity

OBJECTIVE

In the search for optimal biomarkers of excessive drinking, only a few studies have been conducted to compare the relationships between ethanol consumption, liver status, and various laboratory markers of ethanol-induced diseases.

MATERIAL AND METHODS

Concentrations of carbohydrate-deficient transferrin (%CDT and CDTect methods), serum sialic acid (SA), gamma-glutamyl transferase (gamma-GT), aspartate aminotransferase (ASAT), mean corpuscular volume (MCV), and a marker of fibrogenesis (PIIINP) were studied in 102 alcoholics with (n=59) or without (n=43) alcoholic liver disease. Controls were 34 healthy volunteers who were either social drinkers or abstainers.

RESULTS

Although concentrations of all markers were significantly higher in the alcoholic patients than in the healthy controls, their diagnostic characteristics showed a considerable degree of variation. The %CDT, SA, and MCV showed the strongest correlations with the amount of recent alcohol intake. The presence of liver pathology notably influenced the results of CDTect, GT, ASAT, and PIIINP. In ROC analyses, the highest rates of diagnostic accuracy for detecting hazardous drinking were reached with GT (0.94), CDT (0.86), and SA (0.85), followed by MCV (0.79) and ASAT (0.77). Upon abstinence, the estimated times for normalization varied between 10 days (CDTect) and 25 days (GT).

CONCLUSIONS

Our data suggest distinct differences in the clinical characteristics of biological markers of ethanol consumption. While the overall accuracy of CDT and GT appear to be highest in the detection of problem drinking, serum SA and PIIINP measurements are of further value when the effects of liver pathology and ethanol drinking need to be differentiated.

Carbohydrate-deficient transferrin (CDT)--a biomarker for long-term alcohol consumption

Carbohydrate-deficient transferrin (CDT) is a biomarker for chronic alcohol intake of more than 60 g ethanol/d. It has been reported to be superior to conventional markers like gamma-glutamyltransferase (GGT) and mean corpuscular volume MCV). This review covers theoretical and analytical aspects, with data from controlled drinking experiments and from different population subgroups such as subjects with different liver diseases or different drinking patterns. CDT determinations are particularly indicated in (1) cases of chronic alcohol consumption and relapses after withdrawal, (2) license reapplication after driving under alcohol influence, (3) differentiating patients with enzyme-inducing medication from those with alcohol abuse, 4) congenital disorders of glycosylation such as carbohydrate-deficient glycoprotein syndrome Ia (CDGS Ia), and (5) patients treated for galactosemia. The main advantage of CDT is its high specificity, as evidenced in combination with increased alcohol consumption. CDT values are not markedly influenced by medication except in immunosuppressed patients, who may show low CDT values. In general, CDT values appear less elevated after alcohol intake in women. The main disadvantage is the relatively low sensitivity. Hence, this parameter is not suitable for screening for subjects with alcohol abuse in the general population. As CDT, GGT, and MCV are connected with chronic alcohol consumption by different pathophysiological mechanisms, a combination of these parameters will further improve the diagnostic value.

Pathogenesis and management of alcoholic hepatitis

Alcoholic hepatitis is a potentially life-threatening complication of alcoholic abuse, typically presenting with symptoms and signs of hepatitis in the presence of an alcohol use disorder. The definitive diagnosis requires liver biopsy, but this is not generally required. The pathogenesis is uncertain, but relevant factors include metabolism of alcohol to toxic products, oxidant stress, acetaldehyde adducts, the action of endotoxin on Kupffer cells, and impaired hepatic regeneration. Mild alcoholic hepatitis recovers with abstinence and the long-term prognosis is determined by the underlying disorder of alcohol use. Severe alcoholic hepatitis is recognized by a Maddrey discriminant function >32 and is associated with a short-term mortality rate of almost 50%. Primary therapy is abstinence from alcohol and supportive care. Corticosteroids have been shown to be beneficial in a subset of severely ill patients with concomitant hepatic encephalopathy, but their use remains controversial. Pentoxifylline has been shown in one study to improve short-term survival rates. Other pharmacological interventions, including colchicine, propylthiouracil, calcium channel antagonists, and insulin with glucagon infusions, have not been proven to be beneficial. Nutritional supplementation with available high-calorie, high-protein diets is beneficial, but does not improve mortality. Orthotopic liver transplantation is not indicated for patients presenting with alcoholic hepatitis who have been drinking until the time of admission, but may be considered in those who achieve stable abstinence if liver function fails to recover.

Analysis of carbohydrate-deficient transferrin (CDT) in vitreous humour as a forensic tool for detection of alcohol misuse

Analysis of carbohydrate-deficient transferrin concentration in vitreous humour (VH-CDT) has recently been demonstrated to be useful for diagnosis of pre-mortal alcohol misuse, but more knowledge considering possible methodological problems is warranted. In a forensic sample we examined the stability of VH-CDT during laboratory handling as well as the possible affection of time-dependent changes of total transferrin concentrations in vitreous humour (VH-Transferrin) in the dead body on VH-CDT as indicator of alcohol misuse. By use of a commercial assay designed for serum analysis (CDTect) it was possible to measure VH-CDT with high precision, and detectable amounts were found in 20 of 21 alcoholics and in two of seven controls. The compound was demonstrated to be stable in vitreous humour during laboratory handling, since the results of the first analysis were well reproducible after 4 months storage of the specimens (rs=0.86, P=0.0002). Transferrin concentrations in vitreous humour (VH-Transferrin) correlated to the estimated time since the individual last time had been alive before the forensic examination (rs=0.57, P<0.005). However, in this small sample the discriminating property of VH-CDT as indicator of alcohol misuse was not decisively affected, whether or not the variables "VH-Transferrin" and "estimated time since the individual last time had been alive" were considered in a multivariate logistic regression analysis (minor change in the beta-coefficient from 0.57 to 0.52, P=0.086). We conclude that CDT is stable in vitreous humour during proper laboratory handling and that detection of VH-CDT is primarily a marker of alcohol misuse before death. However, the results of this study do not exclude that time-dependent changes of VH-Transferrin, possibly affecting VH-CDT, may occur in the dead body. VH-CDT analysis should thus, at present, be restricted to cases with rather short post-mortal time interval.

Biochemical markers of alcohol use in pregnant women

OBJECTIVES

To describe the serious health consequences of alcohol (ethanol) use, especially as they relate to pregnancy and the development of fetal alcohol syndrome (FAS) and fetal alcohol effects (FAE). The classic markers of alcohol exposure, including blood/breath alcohol, gamma-glutamyl transferase (gammaGT), mean corpuscular volume (MCV), hemoglobin-associated acetaldehyde (HAA) and carbohydrate deficient transferrin (CDT), are valuable and their methods of analysis are reviewed.

CONCLUSIONS

Since both FAS and FAE represent two of the leading preventable causes of mental retardation and birth defects, identification of alcohol use early in pregnancy is important to avoid adverse fetal outcomes. Unfortunately, the diagnosis of FAS and FAE is usually made after birth, when alcohol damage has become irreversible and permanent. The clinical laboratory can help prevent this damage and make a valuable contribution in assessing prenatal alcohol use. The clinical utility of blood/breath alcohol, gammaGT, MCV, HAA and CDT in alcohol use identification, especially in pregnancy, is substantial. Although none of the markers singularly has adequate sensitivity and specificity for screening, their diagnostic utility increases when measured as a panel. This is especially true in detecting alcohol use in pregnancy where the presence of several positive markers was correlated with the presence of alcohol-related fetal effects.

Questionnaires are better than laboratory tests to screen for current alcohol abuse or dependence in a male inpatient population

OBJECTIVE

To assess the diagnostic performance of the CAGE and AUDIT (Alcohol Use Disorder Identification Test) and its derivatives, and laboratory tests for screening alcohol abuse or dependence in a male medical hospital population.

DESIGN

A diagnostic cross-sectional prevalence study.

SETTING

Three general hospitals and one university hospital.

PATIENTS

All male patients older than 18 years admitted to the hospitals, during a period of 6 weeks, were consecutively included in the study (N = 233).

MEASUREMENTS

Calculation of diagnostic measurements with 95% CI and ROC curves for different scores of CAGE, AUDIT and derivatives, laboratory tests and % Carbohydrate Deficient Transferrin (CDT), using DSM-III-R as the reference standard, derived from the CIDI.

RESULTS

A current diagnosis of alcohol abuse or dependence was found in 29 medical male inpatients, representing 12.4% (95% CI: 8.6-17.5). Ten of these (4.2%) fulfilled criteria of alcohol abuse and 19 (8.2%) the criteria of alcohol dependence. Laboratory tests are useless as screening tools with sensitivities between 10% (%CDT) and 52% (GammaGT). Only the Fiveshot questionnaire seems to yield reasonable diagnostic parameters at the recommended cutpoint of > or = 2.5 with a sensitivity of 79.3% and a specificity of 87.7%.

CONCLUSIONS

With a prevalence of 12.4%, our results are similar with other published studies for alcohol abuse and dependence according DSM criteria. The AUDIT as well as the Fiveshot seems to have the best diagnostic properties in this male medical inpatient population, and regarding to brief interventions, these questionnaires can be used as screening instruments as well as opportunities to talk about alcohol problems with admitted patients.

Separation of human serum transferrins with different iron-binding states by high-performance liquid chromatography using a pyridinium polymer column

Four molecular forms of transferrins with different iron-binding states were separated by HPLC using a pyridinium polymer column. The elution order was monoferric transferrin bound to the C-site, holotransferrin, apotransferrin and monoferric transferrin bound to the N-site. Human sera were also analyzed with the column, and ICP-MS combined with HPLC was used to detect iron in each peak. Transferrin peaks separated by HPLC were also confirmed by an immunological method. The percentages of iron saturation in transferrins obtained by the HPLC method were compared with the values calculated from clinical data.

Carbohydrate-deficient transferrin (CDT) determination by nephelometry using a commercial kit. Analytical and diagnostic aspects

Carbohydrate-deficient transferrin (CDT) has been proposed as the most efficient marker of alcohol abuse. Absolute and relative concentrations of CDT were measured with a commercial assay (%CDTTIA from AXIS-Shield, Oslo, Norway) using rate nephelometry for transferrin determination. One hundred eighty-eight alcoholic patients (154 males, 34 females) and 132 control patients (113 males, 19 females) were included in the study. Within-run and day-to-day imprecision were 3.15% and 9.77%, respectively. The calibration curve was stable for more than 4 months with a shift below 5%. The commercial assay lacked sensitivity (Se = 0.48), but was highly specific (Sp = 0.98). Lowering the cut-off from 6% to 4.6% raised the sensitivity of the %CDTTIA test to 0.76 with a specificity of 0.90. We conclude that this adaptation to the Array Protein System (Beckman-Coulter) is suitable for routine use and offers precise results. It, however, requires an adaptation of the cut-off value for patients and of the target value for kit controls.

Determination of Carbohydrate-deficient Transferrin Using Capillary Zone Electrophoresis

Background: Current methods for carbohydrate-deficient transferrin (CDT) often suffer from low precision, complexity, or risk of false positives attributable to genetic variants. In this study, a new capillary zone electrophoresis (CZE) method for CDT was developed.

Methods: CZE was performed on a P/ACE 5000 using fused-silica capillaries [50 μm (i.d.) × 47 cm] and the CEOFIX CDT buffer system with addition of 50 μL of anti-C3c and 10 μL of anti-hemoglobin. Native sera were loaded by high-pressure injection for 3 s, separated at 28 kV over 12 min, and monitored at 214 nm.

Results: CDT was completely resolved by differences in migration times (di-trisialotransferrin, 9.86 ± 0.05 min; monosialotransferrin, 9.72 ± 0.05 min; asialotransferrin, 9.52 ± 0.04 min), with a CV of 0.15%. The number of theoretical plates was 312 000 ± 21 000 for the mono- and 199 000 ± 6500 for the di-trisialylated transferrin. Genetic CB and CD variants showed prominent peaks with migration times of 10.12 ± 0.06 and 9.89 ± 0.03 min, respectively, and the carbohydrate-deficient glycoprotein syndrome could be detected, excluding false-positive results. CZE results (as a percentage; y) correlated with the Axis %CDT TIATM (x) values by Deming regression analysis: y = 1.92x − 7.29; r = 0.89. CDT values in 130 healthy nonalcoholics were determined. The 2.5th and 97.5th percentiles were 1.84% and 6.79%.

Conclusions: CZE without sample pretreatment can determine CDT with good precision, allows detection of variants, and correlates with ion-exchange chromatography.

Investigation by Isoelectric Focusing of the Initial Carbohydrate-deficient Transferrin (CDT) and non-CDT Transferrin Isoform Fractionation Step Involved in Determination of CDT by the ChronAlcoI.D. Assay

Background: The introduction of a new set of reagents for the determination of carbohydrate-deficient transferrin (CDT) as a marker of chronic alcohol abuse requires an independent evaluation of the analytic specificity of the test. This information is needed for correct interpretation and classification of test results.

Methods: Isoelectric focusing on the PhastSystemTM followed by immunofixation, silver staining, and densitometry was used to validate the initial transferrin isoform fractionation step on anion-exchange microcolumns involved in the ChronAlcoI.D.TM assay.

Results: The in vitro transferrin iron load was complete and stable. The CDT and non-CDT transferrin fractionation on anion-exchange microcolumns was reliable and reproducible (CV ≤10%). Except for quantitatively unimportant traces of trisialo-Fe2-transferrin (&lt;5% of total CDT), only asialo-, mono-, and disialo-Fe2-transferrin were detected in the microcolumn eluates (n = 170). There was a loss of proportionally similar amounts of asialo-Fe2-transferrin (during column rinsing) and disialo-Fe2-transferrin (on the anion exchanger). Thus, the peak height ratios for disialo- and asialo-Fe2-transferrin did not change from &gt;1 (serum) to &lt;1 (eluates) as described for the CDTect assays. The transferrin patterns in the ChronAlcoI.D. eluates were representative of those in serum. Transferrin D variants with isoelectric points close to that of trisialo-Fe2-transferrin C1 did not cause overdetermination of CDT by the ChronAlcoI.D. test.

Conclusions: The initial CDT and non-CDT fractionation step involved in determination of CDT by the ChronAlcoI.D. assay is efficient for eliminating non-CDT transferrins from serum before quantification of CDT in the final turbidimetric immunoassay. We recommend IEF for validation of other (commercial) CDT analysis methods and of odd CDT results.